150 



INSECTS INJURIOUS TO THE PEAR. 



usually draws two leaves together and fastens them with 

 silken fibres, or else folds one up and eats the surface, making 



unsightly blotches, which 

 Fig. 156. Fig. 157. disfigure and injure the 



leaves. About the mid- 

 dle of August, the larva 

 changes to a long, slender chrysalis within this mine (Fig. 

 157, also magnified). The moths appear a few days after- 

 wards. 



When its wings are expanded, the moth (Fig. 158, en- 

 larged) measures about one-third of an inch across. The 



fore wings are dark gray, with a round 

 blackish spot on the middle of the inner 

 edge\of tho wing, which is not shown 

 in the figure, also an eye-like spot on 

 the outer edge, with a black pupil. 



As the season advances, these insects 

 sometimes become very abundant, and 

 towards the end of autumn a large pro- 

 portion of the leaves of the pear and apple trees become 

 blotched and disfigured from their work. Since they pass the 

 winter in the larval or chrysalis condition in their leafy en- 

 closures, their numbers may be materially reduced by gathering 

 all the fallen leaves in the autumn and burning them. 



Fig. 158. 



No. 75. — The Pear-tree Slug. 



Selaiidria cerasi Peck. 



In the year 1790, Prof. Peck, of Massachusetts, wrote a 

 pamphlet entitled ^^ Natural History of the Slug-worm/^ 

 which was printed in Boston the same year by order of the 

 Massachusetts Agricultural Society and was awarded the So- 

 ciety's premium of fifty dollars and a gold medal. Although 

 more than ninety years have passed since that pamphlet 

 was written, not much has been added in the interval to our 

 knowledge of the history and habits of this insect. In the 

 mean time, however, it has spread over the greater portion of 



